Analyzing the Impact of Contact Resistance in Graphene–Nb₂O₅ Photogating Detectors

The photogating effect in photodetectors enhances the figures of merit, but graphene-based photodetectors with photogating effect struggle to achieve high responsivity and low contact resistance. This study investigates the impact of the fabrication sequence on the performance of graphene–niobium pentoxide (Nb2O5) photogating detectors. By comparing two different process flows, we demonstrate that altering the sequence of fabrication steps can lead to significant variations in contact resistance, directly affecting the responsivity and speed of the device. Our optimized fabrication process achieves a responsivity of 25 A/W, a rise time of 1.8 ms, and a contact resistance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$470 \; \Omega \cdot \mu $ </tex-math></inline-formula>m. These findings offer valuable insights for optimizing high-performance graphene-based photodetectors.